Q121 / 160 · JIPMER 2006 · Physics

Radius of first Bohr orbit is $r$. What is the radius of 2 nd Bohr orbit?

  • A
    $8 r$
  • B
    $2 r$
  • Correct answer
    C
    $4 r$
  • D
    $2 \sqrt{2} r$

Solution

Radius of Bohr orbit $\begin{array}{l} r \propto n^2 \\ \frac{r_1}{r_2} =\left(\frac{n_1}{n_2}\right)^2 \\ \Rightarrow \frac{r}{r_2} =\left(\frac{1}{2}\right)^2 \\ \Rightarrow \frac{r}{r_2} =\frac{1}{4} \\ \Rightarrow r_2 =4 r .\end{array}$

Hence, the correct answer is option: 'C'.

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